Two former Commissioners of the Metropolitan Police and an ex-head of counter terrorism at Scotland Yard were among signatories of a letter to this newspaper calling for tighter border procedures to “make Britons safer”.

A report recently published by National Audit Office, the watchdog for government spending, discussing the state of the country’s borders detailed trends in spending since the Tories took power in 2010.

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It warned that while spending on Border Force dropped from £616 million in 2012 to £525 million in 2015 the number of people coming into Britain each year was now 12 million higher.

“The Home Office is having to manage this increase in demand alongside budget cuts,” the independent officials concluded.

The funding looks set to become increasingly stretched with the number of people coming to the UK expected to increase by 2 per cent a year in the future.

Critics questioned whether the government should be cutting funding when the amount of people being processed at the border is set to soar.

“Weakening our Border Force is a reckless gamble with public safety. We need more, not less Border guards to keep out those who would national security at risk.”

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A Home Office spokesman said: “It is simply not the case that a reduction in the amount spent per customer travelling to the UK is in any way jeopardising UK security.

“In fact, the NAO figures show that reforms made in recent years have made Border Force a more efficient organisation that provides better value for money for the taxpayer.

“The organisation has improved command and control, brought in new leadership at headquarters and ports across the country and made much greater use of modern technologies to improve security, benefit passengers and deliver efficiencies.

“Border Force has achieved this while ensuring that full checks are carried out on 100 per cent of passengers at passport control.”

Last week it emerged Theresa May has ordered a shake-up of Britain’s coastal defences amid fears migrants are increasingly trying to access the UK's largely unprotected coastline using private boats.

The Home Secretary said that Britain is preparing to increase its “maritime capacity” to deal with migrants attempting to land on the Kent coast.

The disclosure suggests the Home Office has been stung by criticism of the way Britain’s borders are policed.